Elalexander,
My granddaughter is three (3) feet tall and four (4) years old and she loves our horses. Being a grand parent I think that it is our responsibility to spoil the grandchildren as much as we can and whenever we can! One thing we do for them every year is that we send them to children's horse camp to take private lessons. They learn rules, how to ride, and how to take care horses from their coach. Given a good learning environment, young kids become good rider over night and having great time doing it.